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### Description <!-- Explain what you did, what you expected to happen, and what actually happened. --> We have a rare crash in kamailio v5.3 running on Debian Buster in production environment. The crash (segmentation fault) happens while app_json module is writing accounting data to syslog upon receiving ACK for successful INVITE transaction over IPv6 UDP socket.

### Troubleshooting We checked the server health and service load at the time of crash, everything looks normal. We inspected the core dump generated by kamailio, and it seems that there is some sort of race condition causing the crash, the ACK completes the INVITE transaction, so kamailio was fetching the transaction data from memory to write accounting record to syslog, however, that data is corrupted or deleted by some other kamailio process. We do not see anything unusual in kamailio log related to crash. Perhaps it is related to this older but [unresolved crash report](https://github.com/kamailio/kamailio/issues/2998).

#### Reproduction No, we are unable to reproduce it in our lab.

<!-- If the issue can be reproduced, describe how it can be done. -->

#### Debugging Data

<!-- If you got a core dump, use gdb to extract troubleshooting data - full backtrace, local variables and the list of the code at the issue location.

gdb /path/to/kamailio /path/to/corefile bt full info locals list

If you are familiar with gdb, feel free to attach more of what you consider to be relevant. --> Output of `bt full` (first 16 function traces),

```gdb #0 0x0000561a11a47ec7 in match_by_name (avp=0xd, id=52, name=0x7ffccc7967f8) at core/usr_avp.c:379 avp_name = 0x7f10ead4f190 #1 0x0000561a11a48d15 in search_next_avp (s=0x7ffccc7967f0, val=0x7ffccc7967d0) at core/usr_avp.c:500 matched = 0 avp = 0x7f10ead4f180 list = 0x7f10dc3196a8 __func__ = "search_next_avp" #2 0x0000561a11a486d1 in search_avp (ident=..., val=0x7ffccc7967d0, state=0x7ffccc7967f0) at core/usr_avp.c:466 ret = 0x7f10ead4f180 st = {flags = 273, id = 10, name = {n = -567873331, s = {s = 0x7f11de26f0cd "mapped_identity_user)", len = 20}, re = 0x7f11de26f0cd}, avp = 0x7f10f0114820} list = 0x7f10f4d2b208 __func__ = "search_avp" #3 0x0000561a11a4804b in search_first_avp (flags=1, name=..., val=0x7ffccc7967d0, s=0x7ffccc7967f0) at core/usr_avp.c:415 id = {flags = 1, name = {n = -573917191, s = {s = 0x7f11ddcab7f9 "from_mandant);tm", len = 12}, re = 0x7f11ddcab7f9}, index = 0} #4 0x00007f11dcfb0392 in pv_get_avp (msg=0x7f11de70c4b0, param=0x7f11de6cf7b0, res=0x7ffccc796930) at pv_core.c:1793 name_type = 1 avp_name = {n = -573917191, s = {s = 0x7f11ddcab7f9 "from_mandant);tm", len = 12}, re = 0x7f11ddcab7f9} avp_value = {n = -563284264, s = {s = 0x7f11de6cf6d8 "", len = -563034960}, re = 0x7f11de6cf6d8} avp = 0x2000000 avp_value0 = {n = -864458672, s = {s = 0x7ffccc796850 "\300hy\314\374\177", len = -587590620}, re = 0x7ffccc796850} avp0 = 0x7f11dcd1bc90 <val_arr+336> idx = 0 idxf = 0 p = 0x14d0960 <error: Cannot access memory at address 0x14d0960> p_ini = 0x8f6c38 <error: Cannot access memory at address 0x8f6c38> p_size = 22042 n = 0 state = {flags = 497, id = 52, name = {n = -573917191, s = {s = 0x7f11ddcab7f9 "from_mandant);tm", len = 12}, re = 0x7f11ddcab7f9}, avp = 0xd} __func__ = "pv_get_avp" #5 0x0000561a11a77f17 in pv_get_spec_value (msg=0x7f11de70c4b0, sp=0x7f11de6cf798, value=0x7ffccc796930) at core/pvapi.c:1404 ret = 0 __func__ = "pv_get_spec_value" #6 0x00007f11dcd0c43a in extra2strar (extra=0x7f11de6cf788, rq=0x7f11de70c4b0, val_arr=0x7f11dcd1bb90 <val_arr+80>, int_arr=0x7f11dcd1c4d4 <int_arr+20>, type_arr=0x7f11dcd1c725 <type_arr+5> "\002\002\002\002\002\002\002\002\001") at acc_extra.c:222 value = {rs = {s = 0x0, len = 0}, ri = 0, flags = 0} n = 18 i = 0 __func__ = "extra2strar" #7 0x00007f11dc2afc85 in acc_json_send_request (req=0x7f11de70c4b0, inf=0x7ffccc796af0) at acc_json_mod.c:308 attr_cnt = 5 i = 5 m = 0 o = 0 object = 0x561a13e7b7f0 __func__ = "acc_json_send_request" extra = 0x561a11c6f34a #8 0x00007f11dcce5a84 in acc_run_engines (msg=0x7f11de70c4b0, type=0, reset=0x0) at acc.c:581 inf = {env = 0x7f11dcd423a0 <acc_env>, varr = 0x7f11dcd1bb40 <val_arr>, iarr = 0x7f11dcd1c4c0 <int_arr>, tarr = 0x7f11dcd1c720 <type_arr> "\002\002\002\002\001\002\002\002\002\002\002\002\002\001", leg_info = 0x0} e = 0x7f11de6cfa10 __func__ = "acc_run_engines" #9 0x00007f11dccf90a4 in acc_onack (t=0x7f10f4d2b008, req=0x7f10f52e2620, ack=0x7f11de70c4b0, code=-4) at acc_logic.c:657 __func__ = "acc_onack" #10 0x00007f11dccf959c in tmcb_func (t=0x7f10f4d2b008, type=4, ps=0x7ffccc796d10) at acc_logic.c:696 __func__ = "tmcb_func" #11 0x00007f11dd158e87 in run_trans_callbacks_internal (cb_lst=0x7f10f4d2b080, type=4, trans=0x7f10f4d2b008, params=0x7ffccc796d10) at t_hooks.c:254 cbp = 0x7f10f70688d8 backup_from = 0x561a11d83f30 <def_list+16> backup_to = 0x561a11d83f38 <def_list+24> backup_dom_from = 0x561a11d83f40 <def_list+32> backup_dom_to = 0x561a11d83f48 <def_list+40> backup_uri_from = 0x561a11d83f20 <def_list> backup_uri_to = 0x561a11d83f28 <def_list+8> backup_xavps = 0x561a11d16180 <_xavp_list_head> __func__ = "run_trans_callbacks_internal" #12 0x00007f11dd158fae in run_trans_callbacks (type=4, trans=0x7f10f4d2b008, req=0x7f11de70c4b0, rpl=0x0, code=-4) at t_hooks.c:279 params = {req = 0x7f11de70c4b0, rpl = 0x0, param = 0x7f10f70688e8, code = -4, flags = 0, branch = 0, t_rbuf = 0x0, dst = 0x0, send_buf = {s = 0x0, len = 0}} #13 0x00007f11dd0bd4b4 in t_newtran (p_msg=0x7f11de70c4b0) at t_lookup.c:1437 lret = -2 my_err = -562995536 canceled = 0 __func__ = "t_newtran" #14 0x00007f11dd14fb4b in t_relay_to (p_msg=0x7f11de70c4b0, proxy=0x0, proto=0, replicate=0) at t_funcs.c:243 ret = 0 new_tran = 32764 t = 0x7f11de70c4b0 dst = {send_sock = 0x561a11867b90 <_start>, to = {s = {sa_family = 43008, sa_data = "_V\004\271f\377\000\000\000\000\000\000\000"}, sin = {sin_family = 43008, sin_port = 22111, sin_addr = { s_addr = 4284922116}, sin_zero = "\000\000\000\000\000\000\000"}, sin6 = {sin6_family = 43008, sin6_port = 22111, sin6_flowinfo = 4284922116, sin6_addr = {__in6_u = { __u6_addr8 = '\000' <repeats 15 times>, __u6_addr16 = {0, 0, 0, 0, 0, 0, 0, 0}, __u6_addr32 = {0, 0, 0, 0}}}, sin6_scope_id = 294026128}, sas = {ss_family = 43008, __ss_padding = "_V\004\271f\377", '\000' <repeats 16 times>, "\220{\206\021\032V\000\000\260^q\336\021\177\000\000H\221?\336\021\177\000\000\030\203\017\336\021\177", '\000' <repeats 14 times>, "\032V\000\000\000\000\000\002\000\000\000\000\000\250_V\004\271f\377\030e\217", '\000' <repeats 13 times>, "\220{\206\021\032V\000\000p\223y\314\374\177\000", __ss_align = 0}}, id = 0, send_flags = {f = 0, blst_imask = 0}, proto = -128 '\200', proto_pad0 = 111 'o', proto_pad1 = -13191} port = 0 host = {s = 0x2 <error: Cannot access memory at address 0x2>, len = 0} comp = 0 __func__ = "t_relay_to" #15 0x00007f11dd1737b4 in _w_t_relay_to (p_msg=0x7f11de70c4b0, proxy=0x0, force_proto=0) at tm.c:1691 t = 0x7f11de70c4b0 res = 0 __func__ = "_w_t_relay_to" #16 0x00007f11dd174aab in w_t_relay (p_msg=0x7f11de70c4b0, _foo=0x0, _bar=0x0) at tm.c:1891 No locals.

``` Module parameters for `acc_json`,

```python # -- acc_json CDR parameters -- modparam("acc_json", "acc_output_syslog", 1) modparam("acc_json", "acc_flag", 1) modparam("acc_json", "acc_log_facility", ACC_JSON_FACILITY) modparam("acc_json", "acc_extra", "iu=$ou;ou=$ru;f=$fu;t=$tu;cq=$cs;id=$avp(identity_user);mi=$avp(mapped_identity_user);fp=$avp(from_provider);fs=$mf;ld=$avp(lastdst);u1=$ua;u2=$avp(ua_rsp);x1=$hdr(X-RTP-Stat);x2=$avp(xrtp_rsp);xt1=$hdr(X-RTP-Stat-Add);xt2=$avp(xrtp_add_rsp);tt=$avp(target);ct=$ct;fm=$avp(from_mandant);tm=$avp(to_mandant);mc=$avp(m_target)")

```

#### Log Messages

<!-- Check the syslog file and if there are relevant log messages printed by Kamailio, add them next, or attach to issue, or provide a link to download them (e.g., to a pastebin site). -->

``` Nov 28 16:11:59 sip-proxy2 kamailio[1370]: ALERT: <core> [main.c:766]: handle_sigs(): child process 1596 exited by a signal 11 Nov 28 16:11:59 sip-proxy2 kamailio[1370]: ALERT: <core> [main.c:769]: handle_sigs(): core was generated ```

#### SIP Traffic

<!-- If the issue is exposed by processing specific SIP messages, grab them with ngrep or save in a pcap file, then add them next, or attach to issue, or provide a link to download them (e.g., to a pastebin site). -->

```YAML INVITE sip:4900000000@[xxxx:xxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx];uniq=8ED0C01913346AA654117F901E24D SIP/2.0 Record-Route: sip:[yyyy:yyy:yyy:yyy:yyy:yyy:yyy:yyy];r2=on;lr=on Record-Route: sip:bbb.bbb.bbb.bbb;r2=on;lr=on Record-Route: sip:ccc.ccc.cc.ccc;lr=on;ftag=n6719nbq-CC-1031-OFC-1773;did=637.7591 History-Info: sip:+4900000000@sip-proxy.de;index=1 History-Info: sip:+4900000000@sip-proxy.de;user=phone;index=1.1;np=1 Record-Route: sip:ddd.ddd.ddd.ddd;lr=on Via: SIP/2.0/UDP [yyyy:yyy:yyy:yyy:yyy:yyy:yyy:yyy];branch=z9hG4bKd674.46e0b6bab175e9465a766f3602eb1723.0 Via: SIP/2.0/UDP ccc.ccc.cc.ccc;branch=z9hG4bKd674.fbdcb55027bdeb56205b8bd53e09641b.0 Via: SIP/2.0/UDP ddd.ddd.ddd.ddd;branch=z9hG4bKd674.c1356dc9c4dd64165b1d2a7b6dcc8061.0 Via: SIP/2.0/UDP ee.eee.eee.ee:5060;branch=z9hG4bKud6dm320bogcnc1dqvu0.1 Call-ID: b6a6a84q4nw41b9icb46b1441ccbzcnv@zz.zz.z.zz From: "+491111111111"sip:+491111111111@sip-server.de;transport=udp;user=phone;tag=n6719nbq-CC-1031-OFC-1773 To: "+4900000000"sip:+4900000000@sip-proxy.de;user=phone CSeq: 1 INVITE Max-Forwards: 61 P-Early-Media: supported Contact: sip:+491111111111@ee.eee.eee.ee:5060;user=phone;transport=udp Allow: INVITE,ACK,OPTIONS,BYE,CANCEL,INFO,PRACK,NOTIFY,MESSAGE,REFER,UPDATE Supported: timer Min-SE: 90 Session-Expires: 1800;refresher=uac Content-Length: 550 Content-Type: application/sdp

v=0 o=- 1159782858 1 IN IP6 aaaa:aaa:aaa:a:aaa:aaa:aaa:aa s=- c=IN IP6 aaaa:aaa:aaa:a:aaa:aaa:aaa:aa b=RR:3000 b=RS:1000 b=AS:80 t=0 0 a=rtpengine:dda0c1ad4f21 m=audio 20798 RTP/AVP 9 8 96 0 110 b=RR:1837 b=RS:612 b=AS:80 a=maxptime:240 a=msi:mavodi-0-15b-89-6-ffffffff-b5930000-5e88bfbb24c0a-948-ffffffffffffffff-@ff.fff.fff.f-gg.ggg.ggg.g;UAGLEJ04-24 a=rtpmap:9 G722/8000 a=rtpmap:8 PCMA/8000 a=rtpmap:96 G726-32/8000 a=rtpmap:0 PCMU/8000 a=rtpmap:110 telephone-event/8000 a=fmtp:110 0-15 a=sendrecv a=rtcp:20799 a=ptime:20

SIP/2.0 100 Trying Via: SIP/2.0/UDP [yyyy:yyy:yyy:yyy:yyy:yyy:yyy:yyy];branch=z9hG4bKd674.46e0b6bab175e9465a766f3602eb1723.0 Via: SIP/2.0/UDP ccc.ccc.cc.ccc;branch=z9hG4bKd674.fbdcb55027bdeb56205b8bd53e09641b.0 Via: SIP/2.0/UDP ddd.ddd.ddd.ddd;branch=z9hG4bKd674.c1356dc9c4dd64165b1d2a7b6dcc8061.0 Via: SIP/2.0/UDP ee.eee.eee.ee:5060;branch=z9hG4bKud6dm320bogcnc1dqvu0.1 From: "+491111111111" sip:+491111111111@sip-server.de;user=phone;tag=n6719nbq-CC-1031-OFC-1773 To: "+4900000000" sip:+4900000000@sip-proxy.de;user=phone Call-ID: b6a6a84q4nw41b9icb46b1441ccbzcnv@zz.zz.z.zz CSeq: 1 INVITE User-Agent: AVM FRITZ!Box 7490 (UI) 113.07.29 (Oct 26 2021) Content-Length: 0

SIP/2.0 180 Ringing Via: SIP/2.0/UDP [yyyy:yyy:yyy:yyy:yyy:yyy:yyy:yyy];branch=z9hG4bKd674.46e0b6bab175e9465a766f3602eb1723.0 Via: SIP/2.0/UDP ccc.ccc.cc.ccc;branch=z9hG4bKd674.fbdcb55027bdeb56205b8bd53e09641b.0 Via: SIP/2.0/UDP ddd.ddd.ddd.ddd;branch=z9hG4bKd674.c1356dc9c4dd64165b1d2a7b6dcc8061.0 Via: SIP/2.0/UDP ee.eee.eee.ee:5060;branch=z9hG4bKud6dm320bogcnc1dqvu0.1 Record-Route: sip:[yyyy:yyy:yyy:yyy:yyy:yyy:yyy:yyy];r2=on;lr=on Record-Route: sip:bbb.bbb.bbb.bbb;r2=on;lr=on Record-Route: sip:ccc.ccc.cc.ccc;lr=on;ftag=n6719nbq-CC-1031-OFC-1773;did=637.7591 Record-Route: sip:ddd.ddd.ddd.ddd;lr=on From: "+491111111111" sip:+491111111111@sip-server.de;user=phone;tag=n6719nbq-CC-1031-OFC-1773 To: "+4900000000" sip:+4900000000@sip-proxy.de;user=phone;tag=0D99F03B986ED6CD Call-ID: b6a6a84q4nw41b9icb46b1441ccbzcnv@zz.zz.z.zz CSeq: 1 INVITE Contact: sip:4900000000@[xxxx:xxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx];uniq=8ED0C01913346AA654117F901E24D User-Agent: AVM FRITZ!Box 7490 (UI) 113.07.29 (Oct 26 2021) Content-Length: 0

SIP/2.0 200 OK Via: SIP/2.0/UDP [yyyy:yyy:yyy:yyy:yyy:yyy:yyy:yyy];branch=z9hG4bKd674.46e0b6bab175e9465a766f3602eb1723.0 Via: SIP/2.0/UDP ccc.ccc.cc.ccc;branch=z9hG4bKd674.fbdcb55027bdeb56205b8bd53e09641b.0 Via: SIP/2.0/UDP ddd.ddd.ddd.ddd;branch=z9hG4bKd674.c1356dc9c4dd64165b1d2a7b6dcc8061.0 Via: SIP/2.0/UDP ee.eee.eee.ee:5060;branch=z9hG4bKud6dm320bogcnc1dqvu0.1 Record-Route: sip:[yyyy:yyy:yyy:yyy:yyy:yyy:yyy:yyy];r2=on;lr=on Record-Route: sip:bbb.bbb.bbb.bbb;r2=on;lr=on Record-Route: sip:ccc.ccc.cc.ccc;lr=on;ftag=n6719nbq-CC-1031-OFC-1773;did=637.7591 Record-Route: sip:ddd.ddd.ddd.ddd;lr=on From: "+491111111111" sip:+491111111111@sip-server.de;user=phone;tag=n6719nbq-CC-1031-OFC-1773 To: "+4900000000" sip:+4900000000@sip-proxy.de;user=phone;tag=0D99F03B986ED6CD Call-ID: b6a6a84q4nw41b9icb46b1441ccbzcnv@zz.zz.z.zz CSeq: 1 INVITE Contact: sip:4900000000@[xxxx:xxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx];uniq=8ED0C01913346AA654117F901E24D User-Agent: AVM FRITZ!Box 7490 (UI) 113.07.29 (Oct 26 2021) Supported: 100rel,replaces Allow-Events: telephone-event,refer Allow: INVITE,ACK,OPTIONS,CANCEL,BYE,UPDATE,PRACK,INFO,SUBSCRIBE,NOTIFY,REFER,MESSAGE,PUBLISH Content-Type: application/sdp Accept: application/sdp, multipart/mixed Accept-Encoding: identity Content-Length: 277

v=0 o=user 12824182 12824182 IN IP6 xxxx:xxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx s=- c=IN IP6 xxxx:xxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx t=0 0 m=audio 7078 RTP/AVP 8 110 a=rtpmap:8 PCMA/8000 a=rtpmap:110 telephone-event/8000 a=fmtp:110 0-15 a=sendrecv a=rtcp:7079 a=ptime:20

SIP/2.0 200 OK Via: SIP/2.0/UDP [yyyy:yyy:yyy:yyy:yyy:yyy:yyy:yyy];branch=z9hG4bKd674.46e0b6bab175e9465a766f3602eb1723.0 Via: SIP/2.0/UDP ccc.ccc.cc.ccc;branch=z9hG4bKd674.fbdcb55027bdeb56205b8bd53e09641b.0 Via: SIP/2.0/UDP ddd.ddd.ddd.ddd;branch=z9hG4bKd674.c1356dc9c4dd64165b1d2a7b6dcc8061.0 Via: SIP/2.0/UDP ee.eee.eee.ee:5060;branch=z9hG4bKud6dm320bogcnc1dqvu0.1 Record-Route: sip:[yyyy:yyy:yyy:yyy:yyy:yyy:yyy:yyy];r2=on;lr=on Record-Route: sip:bbb.bbb.bbb.bbb;r2=on;lr=on Record-Route: sip:ccc.ccc.cc.ccc;lr=on;ftag=n6719nbq-CC-1031-OFC-1773;did=637.7591 Record-Route: sip:ddd.ddd.ddd.ddd;lr=on From: "+491111111111" sip:+491111111111@sip-server.de;user=phone;tag=n6719nbq-CC-1031-OFC-1773 To: "+4900000000" sip:+4900000000@sip-proxy.de;user=phone;tag=0D99F03B986ED6CD Call-ID: b6a6a84q4nw41b9icb46b1441ccbzcnv@zz.zz.z.zz CSeq: 1 INVITE Contact: sip:4900000000@[xxxx:xxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx];uniq=8ED0C01913346AA654117F901E24D User-Agent: AVM FRITZ!Box 7490 (UI) 113.07.29 (Oct 26 2021) Supported: 100rel,replaces Allow-Events: telephone-event,refer Allow: INVITE,ACK,OPTIONS,CANCEL,BYE,UPDATE,PRACK,INFO,SUBSCRIBE,NOTIFY,REFER,MESSAGE,PUBLISH Content-Type: application/sdp Accept: application/sdp, multipart/mixed Accept-Encoding: identity Content-Length: 277

v=0 o=user 12824182 12824182 IN IP6 xxxx:xxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx s=- c=IN IP6 xxxx:xxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx t=0 0 m=audio 7078 RTP/AVP 8 110 a=rtpmap:8 PCMA/8000 a=rtpmap:110 telephone-event/8000 a=fmtp:110 0-15 a=sendrecv a=rtcp:7079 a=ptime:20

ACK sip:4900000000@[xxxx:xxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx];uniq=8ED0C01913346AA654117F901E24D SIP/2.0 Record-Route: sip:[yyyy:yyy:yyy:yyy:yyy:yyy:yyy:yyy];r2=on;lr=on Record-Route: sip:bbb.bbb.bbb.bbb;r2=on;lr=on Record-Route: sip:ccc.ccc.cc.ccc;lr=on;ftag=n6719nbq-CC-1031-OFC-1773;did=637.7591 Record-Route: sip:ddd.ddd.ddd.ddd;lr=on Via: SIP/2.0/UDP [yyyy:yyy:yyy:yyy:yyy:yyy:yyy:yyy];branch=z9hG4bKd674.6295c199c1d6f3d7c65df5051cc1bd86.0 Via: SIP/2.0/UDP ccc.ccc.cc.ccc;branch=z9hG4bKd674.9ae26c2d53df7a32d7cc5201eef22b18.0 Via: SIP/2.0/UDP ddd.ddd.ddd.ddd;branch=z9hG4bKd674.398f61cd1fb592c16403d50538fc8421.0 Via: SIP/2.0/UDP ee.eee.eee.ee:5060;branch=z9hG4bK2j5dam10a02iqjq1gn00.1 Call-ID: b6a6a84q4nw41b9icb46b1441ccbzcnv@zz.zz.z.zz From: "+491111111111" sip:+491111111111@sip-server.de;user=phone;tag=n6719nbq-CC-1031-OFC-1773 To: "+4900000000" sip:+4900000000@sip-proxy.de;user=phone;tag=0D99F03B986ED6CD CSeq: 1 ACK Max-Forwards: 61 Content-Length: 0

BYE sip:+491111111111@ee.eee.eee.ee:5060;user=phone;transport=udp SIP/2.0 Via: SIP/2.0/UDP [xxxx:xxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx]:5060;rport;branch=z9hG4bK66826E59C0886604 Route: sip:[yyyy:yyy:yyy:yyy:yyy:yyy:yyy:yyy];r2=on;lr=on Route: sip:bbb.bbb.bbb.bbb;r2=on;lr=on Route: sip:ccc.ccc.cc.ccc;lr=on;ftag=n6719nbq-CC-1031-OFC-1773;did=637.7591 Route: sip:ddd.ddd.ddd.ddd;lr=on From: "+4900000000" sip:+4900000000@sip-proxy.de;user=phone;tag=0D99F03B986ED6CD To: "+491111111111" sip:+491111111111@sip-server.de;user=phone;tag=n6719nbq-CC-1031-OFC-1773 Call-ID: b6a6a84q4nw41b9icb46b1441ccbzcnv@zz.zz.z.zz CSeq: 2 BYE X-RTP-Stat: CS=0;PS=3811;ES=3889;OS=609760;SP=0/0;SO=0;QS=-;PR=3853;ER=3889;OR=616480;CR=0;SR=0;QR=-;PL=0,0;BL=0;LS=0;RB=0/0;SB=-/-;EN=PCMA;DE=PCMA;JI=23,1;DL=67,67,70;IP=[xxxx:xxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx]:7078,[hhhh:hhh:hhh::hhh:hhh:hhh:hh]:20798 X-RTP-Stat-Add: DQ=2;DSS=0;DS=0;PLCS=32;JS=1 X-SIP-Stat: DRT=0;IR=0 Reason: Q.850; cause=16 Max-Forwards: 70 User-Agent: AVM FRITZ!Box 7490 (UI) 113.07.29 (Oct 26 2021) Supported: 100rel,replaces Allow-Events: telephone-event,refer Content-Length: 0

SIP/2.0 200 OK Via: SIP/2.0/UDP [xxxx:xxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx]:5060;received=xxxx:xxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx;rport=5060;branch=z9hG4bK66826E59C0886604 From: "+4900000000" sip:+4900000000@sip-proxy.de;user=phone;tag=0D99F03B986ED6CD To: "+491111111111" sip:+491111111111@sip-server.de;user=phone;tag=n6719nbq-CC-1031-OFC-1773 Call-ID: b6a6a84q4nw41b9icb46b1441ccbzcnv@zz.zz.z.zz CSeq: 2 BYE Record-Route: sip:ddd.ddd.ddd.ddd;lr=on Record-Route: sip:ccc.ccc.cc.ccc;lr=on;ftag=n6719nbq-CC-1031-OFC-1773 Record-Route: sip:bbb.bbb.bbb.bbb;r2=on;lr=on Record-Route: sip:[yyyy:yyy:yyy:yyy:yyy:yyy:yyy:yyy];r2=on;lr=on Content-Length: 0

```

### Possible Solutions

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### Additional Information

* **Kamailio Version** - output of `kamailio -v`

```RUST version: kamailio 5.3.9 (x86_64/linux) flags: USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLACKLIST, HAVE_RESOLV_RES, TLS_PTHREAD_MUTEX_SHARED ADAPTIVE_WAIT_LOOPS 1024, MAX_RECV_BUFFER_SIZE 262144, MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB poll method support: poll, epoll_lt, epoll_et, sigio_rt, select. id: compiled with gcc 8.3.0 ```

* **Operating System**:

<!-- Details about the operating system, the type: Linux (e.g.,: Debian 8.4, Ubuntu 16.04, CentOS 7.1, ...), MacOS, xBSD, Solaris, ...; Kernel details (output of `lsb_release -a` and `uname -a`) -->

```RUST Linux sip-proxy2 4.19.0-22-amd64 #1 SMP Debian 4.19.260-1 (2022-09-29) x86_64 GNU/Linux ```